1. Field of the invention
The present invention relates to a control apparatus for controlling a generator in such a way that vehicle body vibration caused by an engine can be cancelled by generator vibration driven by the engine, and specifically to a vehicle body vibration reduction control apparatus suitable for use in passenger cars so as to reduce vehicle body vibration at engine idling, in particular.
2. Description of the Prior Art
An automotive vehicle engine tends to vibrate at low engine speed in general, and particularly the vibration increases at engine idling. To reduce the vehicle body vibration, a vibration reduction control apparatus has been proposed such that torque fluctuations of the engine crankshaft can be reduced by controlling, exciting current for an alternator (provided for charging a storage battery so that the alternator torque can be generated 180 degrees out-of-phase with the engine crankshaft torque whenever engine crankshaft torque fluctuation increases, as disclosed in Japanese Published Examined (Koho) Appli. No. 63-45498.
In this prior-art apparatus, the vehicle body vibration can be cancelled by increasing torque required to drive the generator in such a way that the generator exciting current is increased according to angular positions of the engine crankshaft, while keeping the exciting current pulse at a constant pulse width.
In the prior-art apparatus, however, since the vibration reduction is controlled without due consideration of the battery storage state, there exists a problem in that the storage battery is damaged or the battery life is shortened due to overcharge of the storage battery.
The reason is as follows: in order to reduce the vehicle body vibration when engine speed fluctuates at low engine speed (e.g. idling), since a relatively large engine torque must be cancelled by the generator torque, the torque required to drive the generator increases. Therefore, the generator exciting current is increased to increase the generator output, so that the storage battery is inevitably subjected to be overcharged.